Electromagnetic Simulation of Missile Exhaust

A simple moment solution is given for the problem of electromagnetic transmission through dielectric-filled slots in a conducting cylindrical shell of arbitrary cross section. The exciting source is assumed to be either a TM plane wave (receive mode) or an electric line current placed inside the shell (transmit mode). The surface-equivalence principle is used to replace the surfaces of the shell and the dielectrics by equivalent surface currents radiating in an unbounded medium. The application of the appropriate boundary conditions yields a set of coupled integral equations for the surface currents. The moment method with pulse expansion and point-matching testing procedures is used to solve the integral equations. Shells of different cross-sectional shapes are considered. Special attention is paid to circular and rectangular shells. In the transmit mode, the total far field transmitted through the slot is computed. In the receive mode, the aperture field and the field at the center of the shell are computed. For the case of air dielectric filling the slots, the computed results are in very good agreement with available published data.